Terrestrial gastropods, such as snails and slugs, consume foliage and are a major cause of plant damage, both in agriculture and in home gardens. Conventional techniques for controlling snails and slugs include picking the pests from foliage by hand, the use of toxic snail baits, and electrical elimination methods.
Picking of snails and slugs from foliage is most effective when done at night or in the early morning hours, as these pests are nocturnal foragers and spend daylight hours in concealment. Hand picking of snails or slugs from foliage is usually accompanied by physical destruction of the pests. The collection of the pests, and the particulars of their subsequent destruction, are distinctly unpleasant to many persons.
Toxic snail baits are available. However, many toxic snail baits are not recommended for use around vegetable or fruit crops. Even those toxic snail baits which are safe around food crops remain effective for only a limited period of time. Regular applications of toxic baits are generally needed to protect plants in a given area.
All toxic snail baits have undesirable features. The use of toxic snail baits may be inadvisable in areas where small children or animals have access to the poison. In addition, many people are adverse to the deliberate spread of toxins into the environment.
Various forms of electrical barriers have been developed for the purpose of repelling or eliminating insects and animals from an area that is to be protected, or in the case of insects in particular, for the purpose of extermination. These prior systems are not particularly adaptable to the easy control of snails and slugs. Such systems require an external source of electrical power such as a battery, or use connections to utility power lines and continuously consume electrical energy. Such systems also tend to be complex, costly, and require a significant amount of maintenance effort.
Aquatic mollusks, crustaceans, and algae pose a problem for freshwater and marine vessels, as well as for other structures which exist in aquatic environments. Biocidal paints and coatings are used on aquatic vessels to minimize the encroachment of flora and fauna onto the surfaces of, for example, boats, piers, power plants and desalinization plants. Aquatic biocidal paints generally function by leaching small amounts of noxious chemicals into the water surrounding the treated surface.